The present invention relates to a method for hot-forming and hardening a sheet-metal component with flanges in a cooled forming tool, and to an apparatus for hot-forming and hardening a sheet-metal component with flanges, wherein the apparatus has a forming tool and at least one auxiliary tool.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
During hot-forming, a metal sheet is heated to a temperature above its recrystallization temperature, i.e., to about 850° C. to 1100° C., and subsequently hot-formed. When the forming tool, which consists of a die and a die-plate, is cooled, the workpiece can be hardened while still in the tool (press-hardening).
After hardening, additional cold-forming or material-removing machining can only be performed at high cost. However, another hot-forming has the disadvantage that the material is subjected to a new structural transformation, wherein the original strengths can no longer be attained.
DE 10 2007 039 096 A1 describes a method for hot-forming a sheet-metal blank, wherein the hot sheet-metal blank projects at least partially over a corresponding blank form in a marginal region, so that this marginal region does not come into contact with cooled parts of the tool when the drawing press tool is closed. The marginal region is then initially not so strongly cooled as to cause hardening. It therefore retains good formability. The marginal region is post-formed in a subsequent post-forming process step by relative movement between tool components and thereby comes into contact with cooled tool regions to promote hardening. Such post-forming is performed by moving either the die or the die-plate relative to additional stationary tool components, or additional tool components can be constructed to be movable for post-forming.
Disadvantageously, flanges with differently oriented bending axes cannot be formed. The prior art only discloses methods where two flanges with different bending axes can be produced with several forming steps which is quite complex. As a particular disadvantage, the workpiece may meanwhile cool down so that it can no longer be hardened.
An additional disadvantage, a coating may have been applied on the workpiece before the forming process. This coating can be damaged in a subsequent forming process or in a forming process having a time offset.
It would therefore be desirable and advantageous to address this problem and to obviate other prior art shortcomings by providing a hot-forming method for implementing a forming process of a sheet-metal blank, with simultaneous forming of marginal regions of the sheet-metal blank into weld flanges having bending axes oriented in different directions. It would also be desirable to provide an apparatus for performing a forming process for producing weld flanges with differently oriented bending axes.